Tomato Hornworms

How to Identify and Get Rid of Tomato Hornworms

Amanda Hill

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Big, fat, and green! Here are tips on how to identify, control, and get rid of tomato hornworms in your garden.

What Are Hornworms?

If you’ve ever grown tomatoes, chances are good that you’ve dealt with these green caterpillar pests. There are two main garden pest species, tomato hornworms and tobacco hornworms, which can be found in most regions of the U.S. and in southern Canada. Both species can ruin your tomato crop in record time! They also feed on other plants in the Solanaceae (nightshade) family: eggplants, peppers, tobacco, and potatoes. They blend in quite easily with the green foliage and feed non-stop, creating spotty and chewed leaves and fruit.

Tomato (and tobacco) hornworms live according to the following life cycle:

In late spring, large adult moths lay eggs on the undersides of foliage, which will hatch within a week. The adult moths are easily recognizable; they’re commonly called sphinx or hummingbird moths.

Caterpillar larvae will hatch in late spring and feed for 4–6 weeks before creating a cocoon, overwintering in their pupal state in the soil. If the weather is warm enough, larvae may only burrow for as little as 2–3 weeks.

Moths will emerge in the spring, and will then lay eggs once again. More than one generation a year may be possible in warmer climates.

Tomato hornworm moth (female). Look out for the moths in late spring. Photo by Didier Descouens/Wikimedia Commons.

Identification

How to Identify Tomato Hornworms

Hornworms can be up to 5 inches long—which can be quite a shock when you first come across one! They do the most damage in the caterpillar—or larval—stage. They are pale green with white and black markings, plus a horn-like protrusion stemming from their rear. (Don’t worry, they aren’t able to sting or bite!) The caterpillar also has eight V-shaped stripes on its green body. Tomato hornworms come from a mottled brown-gray moth (see picture, above).

The larvae blend in really well with the plant greenery. Just get used to a daily patrol, looking for hornworm eggs and small caterpillars. Here are some cues of infestations:

Hornworms tend to start feeding from the top of the plant; look for chewed or missing leaves.

Look closely at the TOP of your tomato leaves for dark green or black droppings left by the larvae feeding on the leaves. Then look at the underside of leaves and you’ll likely find a hornworm.

Look for stems missing some leaves and wilted leaves hanging down. You may find white cocoons and their hornworm hosts nearby.

Tomato hornworm

Tomato vs. Tobacco Hornworms

There are a few species of hornworms that inhabit North American gardens, including tomato hornworms (Manduca quinquemaculata) and tobacco hornworms (Manduca sexta). Both species feed on common garden plants like tomatoes, potatoes, peppers, and eggplants. Here’s how to tell which caterpillar is which:

Tobacco hornworms have black spots lining each of their stripes; tomato hornworms do not.

Tobacco hornworms have a red “horn” on their tail end; tomato hornworms have a black horn.

Can you tell which hornworm this is? (It’s a tobacco hornworm! Notice the white stripes with dotted black lines and a red “horn.”)

Tomato Hornworm Damage

If you see leaves with large holes and severe defoliation, devoured flowers, and/or scarring on fruit surfaces, you might have tomato or tobacco hornworms. The fruit also may be damaged by sunscald because of the reduced foliage cover.

Control and Prevention

How to Get Rid of Tomato Hornworms

Handpicking is an excellent tactic for control if you have the time and patience, or a small garden. The caterpillars are not dangerous and can neither sting nor bite. If you are squeamish about crushing these large insects, drop them into soapy water instead (or feed them to your chickens, if you’ve got a flock).

If the hornworm population or the area of your garden is too large, insecticides can be effective, though they should be a last resort. You can use the organic pesticide Bt (Bacillus thuringiensis), which is a bacterium that acts as a stomach poison on some larval insects (but doesn’t harm other plants or animals). Bt must be ingested by the caterpillars to be effective, and it must be reapplied to plant foliage after rain. Please check with your local Cooperative Extension for a list of approved insecticides in your area.

Insecticidal soaps will also kill hornworms, but the pests need to come into direct contact with the substance.

A tobacco hornworm covered with parasitic wasp eggs.

How to Prevent Tomato Hornworms

Till soil at the beginning and end of each gardening season to destroy overwintering larvae. Tillage has shown to cause up to 90% mortality.

Keep wasps around; a number of species are beneficial insects which feed on hornworms and act as a biological control. You may see hormworms with parasitic wasp larvae attached, which look like grains of rice (see picture, above). These attacked hornworms will continue to feed for a little while, but will soon succumb to their hitchhikers, so it’s wise to leave them alone and let the wasps carry out their life cycle. Alternatively, remove infected hornworms and place them far away from your garden. This way, the wasps will still do their job, but the hornworm won’t continue to damage your crops.

Other beneficial insect, like ladybugs and green lacewings, may feed on young hornworms or hornworm eggs.

To keep hornworms away from your tomato plants next year, try interplanting dill or basil; marigolds are also an excellent companion plant.

They love my jalapenos as much as I do!

I started a container garden this year with red and purple bell peppers, jalapenos in a separate container and a sweet meyer lemon tree in another container. I first came across these nasty guys with the bell pepper plants a few months ago. I thought I had it taken care of with neem oil but yesterday had to throw away all 6 bell pepper plants. Although I inspect my plants every day, today I will be throwing away my jalapeno plant due to the magical overnight appearance of the hornworms feasting on the jalapenos (and I just picked about 15 jalapenos this weekend to freeze, did not notice a thing). Please help me save the Sweet Meyer Lemon tree with any suggestions!!!

Hornworms

Hornworms and Rhubarb

No, tomato hornworms feed primarily on plants in the Solanaceae (nightshade) family, which includes potatoes, eggplant, tomatoes, peppers, and others. Rhubarb is not in this family, so it is not in danger of being devoured by hornworms!

Where to Put Hornworms

Hornworms feed on plants in the Solanaceae family (commonly known as “nightshades”), so they’ll need to be placed on another plant that’s in this family in order to be able to develop into moths. Tomatoes are a nightshade, as are potatoes, eggplants, peppers, and tobacco—but these are all plants that you normally wouldn’t want them to eat! There may be wild Solanaceae in your area, such as jimsonweed, horsenettle, or nightshade itself, where you could move the caterpillars to. However, these plants are poisonous, and thus hard to find.

Hornworms may feed on petunias as well. If you can’t find any wild nightshades, perhaps you could set up a couple petunia plants for the hornworms. Or, in future seasons, plant more tomatoes than you need, designating some as “caterpillar-friendly!”

Horn Worms

I used to experience horn worms but one year I saw the white cocoons on the back. The horn worm had quit eating and soon became dessicated. The horn worm wasp emerged and propagated and I never again had a problem with the horn worm. That was the year I planted golden rod and saw so many tiny insects on it and do believe it attracted the wasp.

Tomato Horn Worms

Tomato and Tobacco Horn Worms make great fish bait. Just place their heads on the pointy end of the fishhook and turn the wrong side out. Bream, Crappie, and Bass love them and it's a good way to get rid of them while catching fish for dinner.

Tomato hornworm?

I'm a long time gardener, and have picked plenty of these guys off tomatoes in July or August, but I'm stumped. Today we found a huge one that had eaten nearly all the leaves off two small perennial geranium plants I was getting ready to plant in my garden. I've never seen them this early before, or eating plants other than tomatoes. Has anyone else had this happen to them? Quite a curiosity for me.

geranium devourer

This is news. Mind you, we would never second-guess a long-time gardener who knows his hornworms but…could it have been a cabbage looper? These small green critters do eat geraniums; we can’t find evidence of hornworms consuming them. Can anybody comment further??

tomato hornworm

I live in western North Carolina and I picked 4 off of my tomatoes this week. I planted this tomatoes in pots from last year so i don't know if there were eggs in the soil from last year. They sure are destructive.

Tomatoe Hornworm

My mother-in-law Mary Joe Taylor taught me this -
When you plant the seeds or the young plants put a Large WHITE Styrofoam or Paper cup with the bottom cut out in the hole so that it is up about 4" out of the ground and put the plant in the cup. Make sure you have at least 4" above ground level of the white cup. These worms are like crickets "They won't cross white" ! Make sure that NONE of the limbs on your tomato plant touch the soil as the worms will cheat and use those leaves to climb up to the plant and then your efforts are for naught. I think that trick with the WHITE cup works on other plants as well as other pest like maybe the cutworm. Try it - I haven't had cutworms in years since using this trick!

white cup defense

Where the Hornworm eggs are

This is my 4th year growing tomatoes. Tomato Hornworms are a problem every year. I am determined to be their nemesis. We use tomato cages and the moths often lay their eggs on leaves near the metal of the cage. I suppose they use the cage for support sometimes. The moths can be largish and the metal of the cages offers more support than tomato leaves. The eggs are usually on the underside of the leaves, but not always. So looking for eggs near the cage metal can be quite productive. Rolling eggs off of a leaf is usually fairly easy and considerably less gross than dealing with the hornworms. Of course, the moths lay elsewhere, so keep an eye out for telltale damage. Cheers!

I pay for worms

JUST GROW TOMATOES

You should just grow some tomato plants in the summer and collect the worms. Then you could keep the worms alive until your reptiles have eaten them all. Just get the ones you grow in a container. I am sure it has to be cheaper than buying them all the time. It is just a thought.

Has anybody tried netting?

I plant tomatoes in large containers on my back deck, and will try netting over each plant to hopefully protect the moths from laying their eggs in the soil. The fact that The Green Menace lays eggs twice a year doesn't help matters. I'll give a heads up if it works.

Attacking my Jalafuego pepper plant

I've noticed this is the first year I've had THWs got them 3 times now on a new jalafuego plant almost destroyed it, grew back just found number 2,3,4. #2 was about an inch long maybe 3mm thick other 2 were fresh hatched worms clear and tinyyy. I can't till because my bell pepper plant is 5 years old and is huge and would love to not destroy it. Anyway add any pepper plant to plants they attack, not just bells sadly :/

Not Just Tomatoes

These devils bypassed my tomatoes and ate my potatoes down to the ground, then infested my datura plants. As these are night-blooming flowers, I am not entirely surprised, but pulling them off by hand is harder than you would think. Those suckers are STRONG. I have a small garden, so hand-picking works well, but planting dill only ended up feeding the grasshoppers. Did nothing to deter hornworms.

it's my first year gardening in Alabama after 20 years in Colorado. Takes some time to identify indigenous pests. A bunch of worms the size and thickness of my middle finger springing up out of nowhere? Didn't expect that.

hornworm problem

As I got older I started container gardening in one side of my driveway figuring it would be easier and less pest. Little did I know
these monster hornworms where more at my door step than I thought.They are a real wrestler when it comes to hand removal
so I now use needle- nose pliers to remove .Four Oxheart tomato plants this summer and removed ten of these rascals.

Horn Worms & holes in my tomatoes

I just went out and checked my 4 pots with tomatoes planted in them. I found a bunch of horn worms and actually one big brown worm that looked similar to a horn worm except for color. I picked off the worms I found and pulled them in half and threw them away but I also found that a lot of my tomatoes had holes in them and many of the holes were very discolored. I cut into one tomato expecting to find a worn or something but there was nothing there. Can you tell me what might have caused these holes in my tomatoes?